Forty farms subjected to a wide range of fertilizer and herbicide treatments were assessed to compare the relationships among farm practices, coffee production and environmental sustainability in one of the most intensively coffee farmed regions of Central America.

A focal question addressed by this study is whether there is an environmental (soil, invertebrate diversity) and coffee production (yield and quality) response to different farmer practices, and whether these relationships are influenced by the farm’s landscape characteristics. Farmers, local Cooperatives, and foreign “volunteers” were engaged in the participatory research program including design, data collection and analysis. Starting in 2007, data were collected through semi-structured interviews and registries on farm practices and farm yields, as well as through field work on plant characteristics such as yield, size and quality, environmental characteristics such as shade tree and ground cover diversity and density, soil and foliar nutrient analyses, landscape characteristics such as percent cover natural habitat, and slope.  Furthermore, ecologically and economically important assemblages of arthropods, including spiders, beetles, flies, and hymenoptera were assessed for diversity and abundance along a gradient of farming practices.

Results/Conclusions

The primary impact of farming practices detected across farms were negative correlations between the quantity of nitrogen fertilizer applied and soil pH, acidity, and soil Calcium concentrations.  Organic farms had lower coffee yields than non-organic farms, but on non-organic farms there was no relationship between synthetic nitrogen applications and yield. Instead, coffee yield was impacted by soil acidity, suggesting that excess nitrogen applications were having a detrimental effect on coffee production.  Shade tree density had a negative impact on coffee plant yield, but only at moderate densities. There was no evidence of a trade off between yield and quality, and many of the fields with highest yield also had coffee that produced the most highly scoring “quality”.  Few overall trends were identified between farmer practices and the broad levels of diversity or abundance of arthropods; rather, responses varied across taxa. For instance, spiders were more sensitive to soil conditions than beetles, and higher parasitic wasp diversity was associated with farms surrounded by more forest patches.  Data and results sharing sessions with local farmers and members/officials of the Cooperative have led farmers to shift their practices away form high synthetic nitrogen and herbicide applications and generated greater local interest in becoming “observers” and experimenters in their coffee fields.